1. Field of the Invention
The present invention relates to an arrangement for determining the position of a hollow section system which is pressed forward, in particular one having a curvature, utilizing measuring apparatus arranged one behind the other in the hollow section system, and at least one measuring point.
2. Description of the Prior Art
In conventional and mechanical underground working or mining, the pressing forward of assembled hollow profile systems, such as pipes or tunnels, is gaining increasing significance. Pressing forward refers to a method in which a hollow section system, of any cross section, composed of several similar structural components is pressed into the earth, generally from a shaft; at the same time, the earth entering the hollow section is loosened and discharged through the hollow section system. A controllable member, for example a cutting edge, is located at the front end of the hollow section system; this member facilitates penetration into the earth, and in its protection the excavation takes place. In this case, the earth present at the face is loosened either by hand or mechanically, and is removed.
The entire system is pressed forward, by the length of one structural component, by the main presses installed in the press shaft. The elongation of the hollow section system takes place cyclically in the press shaft by attaching a new structural component to the end of the existing hollow section system after the retraction of the presses. The installation and pressing forward of the entire hollow section system thus takes place from one point.
For controlling the direction, the putting edge supports at least three control presses. According to the soil conditions, the hollow section system reacts more or less quickly to control measures which are undertaken. For accurate control of the hollow section system which is to be pressed forward, it is necessary to check continuously that the route and gradient are being maintained. In conventional measuring methods, the height and position of the hollow section system must be measured each time from the shaft. The measuring distance in this case becomes constantly longer, so that these methods are very complicated and expensive. Moreover, it is necessary to stop the driving operation during the time when measurements are being carried out. In the case of control corrections after a measurement, there is a danger that control pressures which are introduced bring about an overtravel to the other side of the reference curve, which again makes corrections necessary and possibly leads to an increasing overtravel in both directions. An accurate control therefore consists of prompt recognition of deviations, which must then be compensated for depending on the skill and experience of the operator.
Guide beam systems have become known for the exact guidance of the cutting edge; generally focused light beams are made visible on an indicator panel provided with cross wires at the cutting edge. The operator is then able to control the cutting edge as a function of the deviations on the indicator panel. Since the light beam emitter is arranged to be stationary, but the hollow section system and the cutting edge are pressed forward, in this system the driving operation must continuously be interrupted in order to bring the light beam emitter forward again to the cutting edge, and to calibrate it. This interruption occurs particularly frequently if the section being driven has a curve, since the light beam emitter operates solely on a straight line. Its use is therefore possible with acceptable expense solely in the case of gradients having only a slight curve. The frequent adjustment and new calibration necessary in this case also is very time-consuming, so that, since the driving operation must cease during measuring, the driving speed is low.
In another known method for determining the position of the cutting edge, a transmitter installed in the cutting edge emits pulses, which are detected aboveground. According to classical geodetic methods, the position of the cutting edge is then determined. However, this method can only be used in a restricted manner with sufficient accuracy under built-up areas or under water surfaces. Moreover, it gives information only about the position of the cutting edge, and does not take into consideration a lateral shifting of the hollow section system, which substantially influences the direction of the cutting edge.
The use of a gyrocompass is also known, which is connected to a course recorder, and which is already used for bridging the times between the necessary geodetic point and direction determinations in the hollow section system. However, drifting of the compass falsifies the measurement results, so that a conventional geodetic point and direction determination remains absolutely necessary. Since a gyrocompass detects only the azimuthal alignment of the cutting edge, due to its system, no information about the height of the cutting edge is available.
An object of the present invention is to provide an arrangement of the aforementioned general type which is designed in such a way that it is possible to carry out determinations of the spatial position of a hollow section system, during the pressing forward of the latter, as frequently as desired and in short succession, without the pressing operation being hindered or interrupted.